Connecting rods are typically used within internal combustion engines and cooperatively and movably connect the pistons of the engine to the crankshaft. Particularly, one end of each connecting rod is operatively coupled and/or connected to a piston, and the opposite end of each of the connecting rods is operatively coupled and/or connected to the crankshaft. That is, each connecting rod typically includes an aperture which operatively receives the crankshaft, thereby coupling the connecting rod to a certain portion of the crankshaft. In this manner, the connecting rods cooperatively and communicatively transfer forces from the pistons to the crankshaft, thereby cooperatively causing the crankshaft to be rotatably moved in response to the movement of the pistons.
In order to facilitate the connection and/or placement of a connecting rod upon the crankshaft, the connecting rod is "pulled apart" and/or is "broken" or "fractured" along the diameter of the crankshaft-receiving aperture, thereby creating a first or "rod" portion and second or "cap" portion which are then easily, individually, and selectively disposed around and/or upon the crankshaft. The rod and cap portions are then selectively and fixedly coupled together or "reassembled" by the use of two substantially identical bolts or fasteners. Particularly, a pair of threaded apertures are formed within the rod portion and a pair of apertures are formed within the cap portion. Each aperture of the cap portion is selectively registered and/or aligned with a unique one of the apertures of the rod portion. A fastener is then inserted into each pair of registered or aligned apertures, thereby selectively securing the cap portion to the rod portion and securely disposing the connecting rod upon the crankshaft.
When a connecting rod is "pulled apart" or "fractured", a pair of mating surfaces are respectively formed upon each of the rod and cap portions. These surfaces each have unique surface contours (e.g., distinct ridges, grooves, and/or other "imperfections"). Moreover, each of the pair of surfaces upon the cap portion are adapted to mate with a unique one of the pair of surfaces of the rod portion. Hence, when the connecting rod is reassembled "upon the crankshaft", it is desirable to ensure that each of the surfaces which are formed upon the rod portion are made to respectively and matingly engage a respective and unique one of the surfaces of the cap portion, thereby allowing the cap and the rod portions to be "realigned" or "reconnected" in substantially the same manner as they were originally integrally connected and/or aligned before the break or fracture occurred.
However, when the connecting rod is re-assembled or installed upon a crankshaft by an operator or user, it is typically and relatively difficult to determine the manner in which the rod portion and the cap portion were originally aligned and/or integrally connected before the fracture or "break" occurred (i.e., to determine the proper and/or desired mating engagement of the respective mating surfaces). Hence, the connecting rod is often installed or assembled upon the crankshaft with the rod portion and cap portion being "misaligned" or "reversed" (i.e., the cap and rod portions are not aligned or connected in substantially the same manner as they were originally integrally connected or aligned before the fracture or "break" occurred).
This misalignment is detrimental to the overall operation of the engine. Particularly, during engine operation, the misalignment of the cap and rod portions and of these respective surface portions typically causes the cap portion to move or "shift" with respect to the rod portion. This movement or "shifting" undesirably causes the connecting rod to fail, thereby undesirably damaging the vehicle's engine.
Attempts have been made to ensure that the rod and cap portions are properly aligned during installation. These attempts include, by way of example and without limitation, the use of substantially identical "dowel pins" or substantially identical "knurled bolts". While these attempts do somewhat prevent such undesired misalignment, they require additional and relatively costly "machining" or processing of the connecting rod, and substantially and undesirably increase the overall time required to manufacture and/or assemble the connecting rod.
There is therefore a need to provide a connecting rod and a method for making a connecting rod which overcomes some or all of the previously delineated drawbacks, which substantially ensures that the cap and rod portions of a connecting rod are properly aligned during assembly and/or installation upon a crankshaft, and which is relatively easy and cost-effective to produce.